Both satellites are comparitively close to Mars.  Phobos, the inner
one, moves in an almost circular orbit 9270km from the center of
Mars--closer to its parent planet than any other known satellite. The
strong gravitational pull of Mars resulting from its close proximity
is balanced by Phobos' rapid orbiting.  The revolution period is 7hr
39min 27sec, and Phobos therefore completes one journey around Mars in
less than one sol.  Until the recent discovery of the smaller inner
satellites of Jupiter and Saturn, this was a unique case in the Solar
System.  The orbital velocity of Phobos is incresing very slowly and
it has been suggested that Phobos may be spiralling in towards Mars,
and that it will crask on to the surface in about 100 million years'
time, but this is questionable.

Deimos orbits at a distance of 23400km from the center of Mars.  The
revolution perious is 1day 6hr 21min 16sec and Deimos too has a near
circular orbit.  Both satellites' orbits lie within 2 degrees of the
Martian equatorial plane.  This low inclination means that they cross
the Martian sky at a fixed zenith angle, which depends on the
observer's latitude, throughout the Martian year.  The rotation of
each satellite is synchronous.  When a small, irregular body spins
rapidly in the vicinty of a large body, tidal friction will eventually
act as a brake on the rotation of the smaller body until it is
synchronous with its orbital period around the larger body.

To an observer on Mars neither satellite would be imposing.  Phobos,
with an apparent magnitude of -3.9, would shed about as much light as
Venus does on Earth.  It would cross the sky in only 4.5hr, during
which time it would display more than half its cycle of phases, and it
would travel backwards across the sky, that is from west to east.  The
interval between successive risings would be just over 11hr.  Total
solar eclipses would never occur, though Phobos would pass across the
Sun in transit 1300 times during the Martian year, taking 19sec to
cross from one limb to the other.  The satellite would never rise
above the horizon at any Martian latitude higher than 69 degrees N or
S, and even when above the horizon it would be frequently eclipsed by
the shadow of the parent planet.